Might Britain's High Speed Rail route finally get built? The news has Andrew Martin tingling but the disciples of Betjeman have been let down before, he warns

The Government has just announced the beginning of its consultation on the proposed High Speed Rail route that will be built from 2015.

That is, 2015 or so – in that enlightened, and presumably moneyed, era when the subterranean London expressway, Crossrail, will be close to completion, leaving our civil engineers at a loose end. It will proceed in the first instance from London to Birmingham or – as the Brummies who've been lobbying so hard for the line would probably have it – from Birmingham to London, where it will serve a rebuilt Euston station. It will then fork to Leeds and Manchester in a second stage of building and go to Scotland in a third.

When the announcement was made I felt that same tingle of excitement I'd experienced when Cameron, days after coming to power, first confirmed that he would proceed with the line. Because it is every rail enthusiast's... I was about to say "wet dream" but I think "pipe dream" is more appropriate in this milieu.

The last time I'd experienced this tingle was in the late Seventies, when I would sit on the parapet of St Helen's railway bridge, just south of York station, and watch the Deltics go by. Deltics (introduced 50 years ago this spring) were powerful, roaring diesel-electric locomotives that looked as though they were wearing ray-bans. They worked the East Coast main line and were named after either racehorses or regiments, which is exactly what locomotives should be named after. (In the Nineties, when the PR men had got control of the network, I saw an engine at King's Cross called The Richard and Judy Show). My mate Chris, who spent half his life perched on the parapet of St Helen's railway bridge, could observe the approach of some boxy thing with all the aerodynamic properties of a wardrobe and announce with real animation, Brush Type Four! But the Deltics were the only engines I bothered to spot, and I still have a notebook containing an incomplete list of their names: The King's Own Yorkshire Light Infantry, Nimbus, The Royal Scots Grey. (I always used to wonder whether that last one was a racehorse or a regiment).

I shouldn't be surprised if the withdrawal of the Deltics could be closely correlated with the declining numbers of young men wanting to read engineering at university. In terms of railway glamour they left a very big hole indeed, only partially filled by the arrival of Eurostar, which now runs along the route designated High Speed One, as opposed to 2015 project, which is to be High Speed Two or HS2. I did continue with my railway interest in the post-Deltic era, but in such a way that my excitement over a high speed future is tainted with anxiety...

In adulthood, I began to appreciate trains for much the same reason John Betjeman did: because they represented the past; because they were the underdog; because they were more redolent of the countryside than the town. Today, Britain is the world capital of heritage railways, with hundreds of Quixotic lines dedicated to turning back the clock – so many Titfield Thunderbolts or, in the more mawkish cases, so many Thomas The Tank Engines. It is arguable that this has been the dominant tone of rail enthusiasm for a hundred years and that the preservation movement takes its cue from the early-twentieth century railway romanticism expressed in The Railway Children, where the eponymous youngsters treat the tracks as a playground. In 1908, Hilaire Belloc wrote that "nothing could be more English than a country railway station". In Adlestrop by Edward Thomas, the country station is the peaceful vantage point for the observation of nature: "And willows, willow-herb, and grass/ And meadowsweet, and haycocks dry...'

That was written in 1915 and the point is that while the horror of the Great War was unfolding, the great mental and physical disturbance caused to the country by the building of the main trunk railways was long in the past. Most had been completed by the end of the 1860s and the hewing of those lines had produced a very different sort of poetry. It bemoaned the despoliation of the countryside, the triumphalism of the engineers, and the greed of the speculators – the "Thirst of Gold" that, according to William Wordsworth in A Just Disdain, "rules o'er Britain like a baneful star". That was published in the mid 1840s – the time of the second "railway mania", in the midst of which Dickens published his novel of railway speculation, Dombey and Son. In Staggs's Gardens, north London (a Stag was a railway speculator), the "earthquake" of railway construction has arrived. "There were a hundred thousand shapes and substances of incompleteness, wildly mingled out of their places, upside down, burrowing in the earth, aspiring in the air... as unintelligible as any dream."

It was the building of the London and Birmingham railway's route out of Euston that Dickens had observed... And do those proper nouns ring familiarly? Yes, because HS2 takes us right back to those fraught, elemental days: a brand new route connecting the cities served by the very first trunk route.

But this new one can't follow the route of the existing London-Birmingham line (too crooked, too built-up), and so must veer west, blundering into attractive countryside.

The railways are presuming to change Britain again and so they are upsetting Britain again. The focus of the opposition is upon the effect of the new line on the Chiltern landscape, the beauty of which struck me a few weeks ago when I was pursuing my Betjeman-esque low-speed railway interest. (I was writing a piece about the far north of what used to be the Metropolitan railway and is now the Metropolitan Line. I was at Chesham station, served by a branch that is so bucolic that it's bizarre to see a copy of the London Evening Standard left behind on the seat). My trip to the valley of the Chess had made me realise that when the anti-HS2 campaigners – unified under the banner Stop HS2 – speak of the line as going through "virgin countryside" they are not being as whimsical as I had thought.

They argue that when the line is complete, an area the size of Manchester will have been concreted over. But it does seem as though the historical dynamic is once more with the railways – that HS2 will, as Dickens wrote of its predecessor, be "defiant of all obstacles".

Eric Hobsbawm has observed that in the 1840s the term "railway" became 'a sort of synonym for ultra-modernity... as "atomic" was to be after the Second World War. Today the term – as long as it is prefixed by "high speed" – is once more associated with progressivism, which is perhaps especially important to a government inflicting retrenchment in most other areas.

The Coalition seems completely committed to HS2. Late last year, the transport minister, Philip Hammond, announced £750m seed capital for the development of a project that will be entirely state funded at a cost of... well, nobody knows, but about £20bn just for the leg to Birmingham. Moreover there will be links between the basic north-south route and Heathrow to the west of London and HS1 to the east and south. So it is to be more of a "network" than a line.

For us disciples of Betjeman this is both thrilling and unnerving. Thrilling because, to use a term Betjeman would only have spoken with a curled lip, there is certainly "under-capacity" (it seems to be the modern version of "overcrowding") on the railway routes north and because more cars and more planes are not a civilised answer to the problem. The car and the plane above all have created the giant migraine that is modern British life. But there is also this unease, the vertiginous feeling...

It is already clear that we have puppy-ish sort of government, prone to over-confidence and to acting before thinking – for example over school sports funding, or the privatisation of forests.

So the question occurs with some force: Is this a good idea? Certainly our peer countries – Japan, France, Germany, Italy, Spain – have high speed rail and it has brought economic benefits. But all those countries are bigger than Britain. We already have fast – though not "high speed" – rail connections between our main cities, if only because of their proximity to each other.

At the time of the railway mania, the social reformer Samuel Smiles observed that the railways had in effect made Britain "one sixth" of its former size. A high speed line will produce a further contraction... So how much smaller does Britain need to be? And will the effect be that ever more of the country falls under the shadow of London?

The danger is that the line will allow executives from London to raid the gold that would formerly have belonged to Birmingham. Or that the cultural identity of the Midlands – and I personally can't get much beyond Lenny Henry and Jasper Carrott as it is – will be further diluted.

As the columnist Ian Jack recently pointed out, the Victorian trunk routes ended up in London but emanated from the north. They were the means by which London was supplied with the coal, the very bricks it needed to expand. What can the north offer London today? Going by Philip Hammond's assertion that HS2 will allow "the economies of the Midlands and the North to benefit much more directly from the economic engine of London", the answer in his mind seems to be "much". The motive is honourable. The idea is to use 250mph trains to fix the North-South Divide. David Cameron has said as much. But as the railway commentator and high speed sceptic Christian Wolmar has pointed, the talk of "regeneration" and "non-user benefits" tends to become louder and more nebulous the more the business case in narrow terms of journey-time savings is questioned. Ministers evidently accept the social and environmental benefits of railways as compared to road and air travel. (A substantial programme of railway investment survived the Comprehensive Spending Review). But this position seems to be contradicted by the policy of allowing rail fare rises above inflation, so penalising people for using the most benign method of transport.

I'm sure, in any case, that fares on HS2 will be higher even than the expensive norm, just like those on HS1. Perhaps it will become a sort of elite bankers' train, like the charmless Heathrow Express, with very few families aboard and TV screens pompously relaying news bulletins every five minutes.

And why the Heathrow link? Why invite those rowdy aviation boys to the party? They'll fug up all the rooms with smoke and bring that horrible sound system of theirs – so familiar to millions of light-sleeping Londoners – that they keep going until two in the morning and then crank up again at five-thirty.

Greengague 21, the lobby group for High Speed Rail, is fairly sanguine about this. It argues that the Heathrow spur will to some extent provide an access point to the line for people near Heathrow who have no intention of flying – just as not everyone who goes to Wembley Tube station is going to Wembley Stadium.

The contention is also that while the line will funnel people into the airport, they will not be taking short haul flights, since that market will be have been taken over by the trains. John Stewart, chair of the anti-aviation group, Hacan Clearskies, reminds me that of people who travel by either plane or train between London and Scotland, ninety per cent go by plane. HS2, he believes, will soon fix that, providing that it does finally end up in Scotland. The lesson of other high speed lines, he said with glee, is that they absolutely "kill" the aviation along the route.

Listening to John, who I've known, and agreed with, for years, my confidence in HS2 began to return: "It'll take people out of the air and out of their cars and bring a big saving in emissions and noise."

As for the possible subjugation of Birmingham by London: "Look at Lille, which fought hard to be on the HS1 line between London and Paris. It's thriving as a result."As for Greengauge 21, they talk of a sharp increase in relocations to Birmingham as the most likely consequence.

And there is always another possibility altogether: that HS2 is called off; never built; infinitely deferred. That spectre began flickering on the horizon last month, when the shadow transport secretary, Maria Eagle, said that Labour could not guarantee funding for the project if it wins in 2015. Labour is conducting a "root and branch transport review" with nothing ruled in or out, which I suppose means it is deciding whether there are more votes in cancelling HS2 than sticking with it.

Perhaps the line will take its place alongside those other lost railway dreams: the luxurious, seven-foot track gauge of Isambard Kingdom Brunel, the Victorian Channel Tunnel that Sir Edward Watkin, chair of the Metropolitan railway, commenced digging in 1880 (not personally, obviously), or the prototype, stream-lined, ultra-aerodynamic Tube trains of the late 1930s that looked like something out of Fritz Lang's Metropolis.

How we Betjeman-esque types love talking about those. Our railways have for so long been associated with lost causes that it seems almost wrong to be on the winning side.

There is a proverb that fits the case very well. It begins: "Be careful what you wish for..."

Andrew Martin's latest novel is "The Somme Stations" (Faber and Faber)